1. Field of the Invention
The present invention relates to a technology for using a low visibility information embedding technique to manage a copy history of an original.
2. Description of the Related Art
An image processing technology for processing an image consisting of a latent image region and a background region, and creating printed material from which it is determinable whether or not the printed material is copied material, is disclosed in patent document Japanese Patent Laid-Open No. 2004-228896. In the patent document, in order to adapt a latent image element, which together with a background element constitutes a copy-forgery-inhibited pattern image, to disappear upon copying, while the background element does not disappear even upon copying, the latent image element consists of small dots, and the background element consists of large dots. In particular, in the patent document, by shifting the small dot group with respect to a grid point, additional information (e.g., information for a barcode) can be represented (see FIG. 7).
However, the patent document discloses processing for generating the copy-forgery-inhibited pattern image upon first printing, and therefore the additional information is represented by the small dots only upon the first printing. For this reason, the technique disclosed in the patent document cannot represent new additional information using the small dots, upon copying.